摘要：
The mechanical performance of recycled aggregate concrete (RAC) is investigated. An experiment on the complete stress-strain curve under uniaxial compression loading of RAC is carried out. The experimental results indicate that the peak stress, peak strain, secant modulus of the peak point and original point increase with the strength grade of RAC enhanced. On the contrary, the residual stress of RAC decreases with the strength grade enhancing, and the failure of RAC is often broken at the interface between the recycled aggregate and the mortar matrix. Finally, the constitutive model of stress-strain model of RAC has been constituted, and the results from the constitutive model of stress-strain meet the experiment results very well.
摘要：
According to the characters of RNA secondary structure, we introduce a method for RNA secondary structure alignment by changing the structure alignment to sequence alignment based on a binary coding method. Associating with the proposed coding rules and exclusive-OR operation, we can solve the following problems easily: (i) distinguishing the difference between two sequences; (ii) judging the prefix of a sequence matches the suffix of the other sequence; (iii) judging two sequences have common subsequences; (iv) judging a sequence is the subsequence of another sequence.
关键词：
data compression;discrete cosine transforms;image coding;steganography;support vector machines
摘要：
A JPEG image steganalysis scheme based on joint discrete cosine transform (DCT) domain features is proposed. Intrinsic characteristics of DCT coefficients, such as histogram, intrablock correlation, and interblock correlation, are exploited to construct three feature sets. Support vector machine is utilized to learn and discriminate the difference of features between cover and stego images. First, the three feature sets are investigated separately to reveal their individual capability of attacking steganographic methods. Second, the feature sets are combined to form a joint feature set with better performance. Experimental results demonstrate that all three feature sets individually succeed in attacking the four typical steganographic tools to some extent, with the intrablock feature set performing the best. Furthermore, the comparison experiments show that the jointed feature set not only outperforms the three individual feature sets but also proves to be better than a previous state-of-the-art steganalysis method.
期刊：
MATCH-COMMUNICATIONS IN MATHEMATICAL AND IN COMPUTER CHEMISTRY,2010年64(3):767-782 ISSN：0340-6253
通讯作者：
Chen, Shubo
作者机构：
[Liu, Weijun; Chen, Shubo] Cent S Univ, Coll Math, Changsha 410075, Hunan, Peoples R China.;[Chen, Shubo] Hunan City Univ, Dept Math, Yiyang 413000, Hunan, Peoples R China.
通讯机构：
[Chen, Shubo] C;Cent S Univ, Coll Math, Changsha 410075, Hunan, Peoples R China.
摘要：
For a graph G = (V, E), the modified Schultz index of G is defined as S*(G) = Sigma({u,v}subset of V(G)) (d(G)(u).d(G)(v))d(G)(u,v) where d(G)(u) (or d(u)) is the degree of the vertex u of G, and d(G)(u, v) is the distance between u and v. Let B(n) be the set of bicyclic graph with n vertices. In this paper, we study the modified Schultz index of B(n), graphs in B(n) with the smallest modified Schultz index S*(C) are determined. The corresponding extremal graphs are characterized as well.
关键词：
solvent-free reaction;solid base mixture catalysis;chemoselectivity;aldehyde-ketone reaction
摘要：
Solvent-free reactions of aromatic aldehydes with three representative ketones, including acetophenone, acetone and cyclohexanone, have been examined under the catalysis of a low-cost inorganic base system consisting of NaOH and K(2)CO(3). It was found that the chemoselectivity of the reactions is in close relationship with the composition of the reactants and the double-component catalyst. Under the optimized experimental conditions, 1,2,3,4,5-pentasubstituted cyclohexanols, alpha,beta-unsaturated ketones and Claisen-Schmidt bicondensation products were obtained in high yields. Two Kostanecki's triketones were separated, The composition and structure were affirmed by X-ray crystallographic analysis.
期刊：
Ars Combinatoria,2010年97:241-248 ISSN：0381-7032
通讯作者：
Chen, Shubo
作者机构：
[Chen, Shubo] Hunan City Univ, Dept Math & Comp Sci, Yiyang 413000, Hunan, Peoples R China.;[Chen, Shubo] Cent S Univ, Coll Math, Changsha 410075, Hunan, Peoples R China.;[Zhou, Houqing] Shaoyang Univ, Dept Math, Shaoyang 422000, Hunan, Peoples R China.
通讯机构：
[Chen, Shubo] H;Hunan City Univ, Dept Math & Comp Sci, Yiyang 413000, Hunan, Peoples R China.
摘要：
The Zagreb indices are topological indices of graphs, which defined as, Mi(G) = Σv⋯V(G) (d(v))2, M2(G) = Σuv⋯V(G) (d(u)d(v)). In this paper, we determine the upper and lower bounds for the Zagreb indices of unicyclic graphs in terms of their order and girth. In each case, we characterize the extremal graphs.
作者机构：
[Jiang Jian-qing; Yang Guo-lin] Cent S Univ, Sch Civil & Architectural Engn, Changsha 410075, Hunan, Peoples R China.;[Jiang Jian-qing] Hunan City Univ, Sch Civil Engn, Yiyang 413000, Peoples R China.
通讯机构：
[Jiang Jian-qing] C;Cent S Univ, Sch Civil & Architectural Engn, Changsha 410075, Hunan, Peoples R China.
关键词：
red-sandstone;large-scale field test;mechanical characteristic;strength parameter
摘要：
Large-scale field shear tests on ten specimens of the red-sandstone embankment at a highway in Hunan, China, were performed to examine mechanical characteristics and parameters of red-sandstone. The curves of thrust-displacement, failure mode, and shear strength parameters for red-sandstone with different water contents, different compactions, and different grain size distributions were obtained from the tests. A practical procedure of in-situ test for red-sandstone embankment was proposed to normalize the test equipment and test steps. Based on three-dimensional thrust-sliding limit equilibrium method, the formulas for calculating strength parameters of red-sandstone considering three-dimensional sliding surface were inferred. The results show that red-sandstone has typical complete curves of stress-strain, strain softening, which are caused by the special structure of red-sandstone; water content and compaction are important factors for strength and failure mode of red-sandstone; The average value of cohesion and internal friction angle of the specimens calculated by three-dimensional technique are 21.56 kPa and 29.29°, respectively, and those by traditional two-dimensional method are 25.52 kPa and 33.76°, respectively.
作者机构：
[Xiao, Cui'e] Cent S Univ, Sch Math Sci & Comp Technol, Changsha 410075, Hunan, Peoples R China.;[Liu, Zhenhai] Guangxi Univ Nationalities, Sch Math & Comp Sci, Nanning 530006, Peoples R China.;[Xiao, Cui'e] Hunan City Univ, Dept Math & Computat Sci, Yiyang 413000, Peoples R China.
通讯机构：
[Liu, Zhenhai] G;Guangxi Univ Nationalities, Sch Math & Comp Sci, Nanning 530006, Peoples R China.
关键词：
Elliptic hemivariational inequality;Inverse coefficient problem;Existence of quasisolution
摘要：
This paper is devoted to a class of inverse coefficient problems for nonlinear elliptic hemivariational inequalities. The unknown coefficient of elliptic hemivariational inequalities depends on the gradient of the solution and belongs to a set of admissible coefficients. It is shown that the nonlinear elliptic hemivariational inequalities are uniquely solvable for the given class of coefficients. The result of existence of quasisolutions of the inverse problems is obtained.
摘要：
In order to determine the relationship among energy consumption of rock and its fragmentation, dynamic strength and strain rate, granite, sandstone and limestone specimens were chosen and tested on large-diameter split Hopkinson pressure bar (SHPB) equipment with half-sine waveform loading at the strain rates ranging from 40 to 150 s−1. With recorded signals, the energy consumption, strain rate and dynamic strength were analyzed. And the fragmentation behaviors of specimens were investigated. The experimental results show that the energy consumption density of rock increases linearly with the total incident energy. The energy consumption density is of an exponent relationship with the average size of rock fragments. The higher the energy consumption density, the more serious the fragmentation, and the better the gradation of fragments. The energy consumption density takes a good logarithm relationship with the dynamic strength of rock. The dynamic strength of rock increases with the increase of strain rate, indicating higher strain rate sensitivity.
作者：
Li Wenbin*;Pan Qinglin;Zou Liang;Liang Wenjie;He Yunbin;...
期刊：
稀有金属(英文版),2009年28(1):102-106 ISSN：1001-0521
通讯作者：
Li Wenbin
作者机构：
[Pan Qinglin; Li Wenbin; Liang Wenjie; Zou Liang; He Yunbin; Liu Junsheng] Cent S Univ, Sch Mat Sci & Engn, Changsha 410083, Hunan, Peoples R China.;[Li Wenbin] Hunan City Univ, Dept Civil Engn, Yiyang 413000, Peoples R China.
通讯机构：
[Li Wenbin] C;Cent S Univ, Sch Mat Sci & Engn, Changsha 410083, Hunan, Peoples R China.
摘要：
Five kinds of Al-Zn-Mg-Cu-Zr based alloys with different Sc additions were prepared by ingot metallurgy. The effects of minor Sc on the microstructure and mechanical properties of Al-Zn-Mg-Cu-Zr based alloys were investigated using tensile tests, optical microscopy (OM), and transmission electron microscopy (TEM). The results show that the ultimate tensile strength and yield strength are improved by 94 and 110 MPa, respectively, and the elongation to failure remains at a reasonable extent (11.1%) in the Al-Zn-Mg-Cu-Zr based alloy with 0.21 wt.% Sc addition after solution heat treatment at 475°C for 40 min and then aged at 120°C for 24 h. The addition of minor Sc induces the formation of Al3(Sc,Zr) particles, which are highly effective in refining the cast microstructures, retarding recrystallization, and pinning dislocations. The increment of strength is attributed mainly to fine grain strengthening, precipitation strengthening of Al3(Sc,Zr) particles, and substructure strengthening.
作者机构：
[Qi, Liqun] Hong Kong Polytech Univ, Dept Appl Math, Kowloon, Hong Kong, Peoples R China.;[Wang, Fei] Hunan City Univ, Dept Math, Yiyang, Hunan, Peoples R China.;[Wang, Yiju] Qufu Normal Univ, Sch Operat Res & Management Sci, Rizhao 276800, Shandong, Peoples R China.
通讯机构：
[Qi, Liqun] H;Hong Kong Polytech Univ, Dept Appl Math, Kowloon, Hong Kong, Peoples R China.
摘要：
As a global polynomial optimization problem, the best rank-one approximation to higher order tensors has extensive engineering and statistical applications. Different from traditional optimization solution methods, in this paper, we propose some Z-eigenvalue methods for solving this problem. We first propose a direct Z-eigenvalue method for this problem when the dimension is two. In multidimensional case, by a conventional descent optimization method, we may find a local minimizer of this problem. Then, by using orthogonal transformations, we convert the underlying supersymmetric tensor to a pseudo-canonical form, which has the same E-eigenvalues and some zero entries. Based upon these, we propose a direct orthogonal transformation Z-eigenvalue method for this problem in the case of order three and dimension three. In the case of order three and higher dimension, we propose a heuristic orthogonal transformation Z-eigenvalue method by improving the local minimum with the lower-dimensional Z-eigenvalue methods, and a heuristic cross-hill Z-eigenvalue method by using the two-dimensional Z-eigenvalue method to find more local minimizers. Numerical experiments show that our methods are efficient and promising.
